'Friendly Fire'

(CNN) -- Two U.S. soldiers were killed and 20 others wounded when a U.S. B-52 bomber missed its target north of Kandahar, Afghanistan, U.S. military officials said Wednesday.

The officials said an "unknown" number of Afghan opposition forces were killed.

Helicopters were evacuating the injured soldiers to hospitals. Officials said the incident happened about 12:30 a.m. ET.

Sources reported intense fighting Wednesday in Kandahar -- the largest remaining Taliban stronghold. Ethnic Pashtun fighters were pressing on, and sources said the airport is partially under the control of Pashtun fighters.

Elsewhere in Afghanistan, anti-Taliban mujahedeen fighters were engaged with a large pocket of al Qaeda fighters Wednesday at the foothills of the Tora Bora mountains in the eastern part of the country, where suspected terrorist mastermind Osama bin Laden might be hiding, their commander said.